head to head
Mario Kart 8 asks more than Looney Tunes: Space Race, and the gap is variance.

Execution · Twitch Chaos
Kart racing where driving skill fights a steady drizzle of random gag items.

Execution · Twitch Chaos
A kart racer where controlled chaos from random items tempers otherwise precise driving skill.
Looney Tunes: Space Race leans Execution (Twitch Chaos); Mario Kart 8 leans Execution (Twitch Chaos).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Looney Tunes: Space Race
Racing lines and drift control still decide most finishes
Mario Kart 8
precise drifting and item timing matter
Looney Tunes: Space Race leans a little harder on reads, though the gap is small.
Looney Tunes: Space Race
Light gag-timing duels against human racers
Mario Kart 8
minimal, mostly reacting not predicting
Mario Kart 8 leans clearly harder on variance.
Looney Tunes: Space Race
Random gag pickups scramble race outcomes
Mario Kart 8
item boxes are heavily randomized
Mario Kart 8 leans a little harder on optimization, though the gap is small.
Looney Tunes: Space Race
Shortcut and track knowledge compound every lap
Mario Kart 8
track lines and item strategy solvable
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.